This invention relates to an alternating current generator used in a vehicle such as an automobile, bus, truck, motorcycle and the like, the generator having a brush holder which is excellent at protecting the brush and the slip ring from corrosion or abrasion.
In a prior art, Japanese Patent Application Preliminary Publication No. sho 59-169350 discloses an alternating current generator for a vehicle. This generator has a brush holder and a separate cylindrical cover member. The brush holder contains brushes which are urged by springs against slip rings on the rotation shaft of a rotor core. The cylindrical cover member encloses the slip rings so that the slip rings are protected from dust and splash of rainwater. The brush holder and the cover member are hermetically adjoined to each other through packing member. However, dislocation of the brush holder or deterioration of the packing member can cause a clearance between the brush holder and the cylindrical cover member, which then introduces outside dust or splash of rainwater into the cover member. This phenomenon accelerates both corrosion of slip rings and abrasion of the brushes.
Some of the conventional generators have a regulator, the earth terminal of which is connected to the serration section of a fastening bolt which fastens the regulator to the frame of the generator. When a nut is turned to be engaged with the fastening bolt, a torque due to the turning of the nut is transferred to the earth terminal. Therefore, there is a tendency for a backlash to occur between the earth terminal and the fastening bolt, resulting in imperfect contact of the earth terminal with the fastening bolt.